This invention relates generally to the field of spray booths, and in particular to spray booths where air is flowed from the ceiling and past the object being sprayed. More specifically, the invention relates to increasing air flow rates around an object being sprayed to increase evaporation rates.
When painting a vehicle or other object, drying or curing times can limit the amount of throughput. One common way to spray a vehicle is by using a spray booth. These booths provide advantages such as reducing particulate, confining paint overspray and evaporated solvents, and reducing drying times. To accelerate drying, air is flowed through the booth and over the vehicle. For waterborne paints, water in the paint travels to the surface to evaporate. As the air flows over the surface of the paint, it tends to enhance evaporation of the water, thereby reducing drying times.
A wide variety of spray booths are in existence. Perhaps the most common types are downdraft and semi-vertical spray booths that use a housing positioned over an open floor grate or an exhaust outlet near the bottom of the walls. Air from the ceiling and any entrained paint overspray and solvents are drawn downward over the vehicle during spraying and drying and are then exhausted through the floor grate or exhaust opening. One example of such a spray booth is described in U.S. Pat. No. 6,533,654, incorporated herein by reference. Typical flow rates may be about 80 to 100 feet per minute over horizontal surfaces. Even at elevated temperatures and a down draft of semi-vertical draft, it can take up to 40 minutes for the entire vehicle to dry sufficiently to permit removal from the spray booth. Until the automobile is dry, it is usually maintained in the spray booth to prevent damage to the soft paint.
To reduce drying times, some have used heaters to increase the temperature within the booth. Others have tried to increase flow rates using nozzles. See, for example, U.S. Pat. No. 5,456,023, the complete disclosure of which is herein incorporated by reference. This invention is related to other techniques for reducing drying and curing times.